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Chapter 2 : Walls

Freeform ferrocement structures begin as a fragile lattice which gradually becomes an internal armature for the actual ferrocement armature.

This stage is interesting for both architect and builder, it is a real pleasure to watch skeletal reinforcing grow from two dimension plans into multi-dimensional space-time. Now the actual sculpture begins.

Most of the structural forces are concentrated at the surfaces, that is how and why modern sailboat masts are hollow. It is also why much of this inner grid is not very necessary after the wall is a finished and well cured. Many very intelligent people have tried to build without the inner heavier bar armature and some of their techniques have been successful, even so, I find using 1.2+ centimeter diameter reinforcing steel is best for maintaining smooth curves (#4 rebar 1/2").

A grey plastic pipe electric conduit is visible lower right. The box of a wall plug installed here branches to other wall plugs and light switches. Shower and toilet plumbing are located at about the line which defines the bottom third of the photo. The toilet vent is positioned between to rebar stubs on the right and the shower vent is visible where it will rise up the outer wall on the left. More plumbing is visible further on in the kitchen area as well.A door will be cut in through the steel to the left of the electric conduit stub, lower right, after the wall is complete. A window will be cut through the wall to the right of the conduit stub. The plumber and electrician enjoyed this work, especially the electrician, she was at work early every day. Both the plumber and the electrician talked about work which would last for many centuries.

Notice the wire at about a 45° angle in the foreground, a few wires such as this may be required to maintain shape. These wires, if needed, are removed when the rebar is completed.

This preliminary lattice could also be bamboo, which would have one layer of chicken wire, positioned in this case on the outside, and then sandwiched with course woven fabric or muslin, instead of welded wire. The bamboo, surrounded by muslin soaked with cement and acrylic, becomes a mold for very strong fiber reinforced tubes. Organic fibers are interesting and fit within the conceptual framework of ferrocement. The ferrocement.com Roof Laboratory, among others, is exploring this subject; a manual like this for that subject is up-to-date. Ferrocement.com Roof Laboratory progress is also on the web, it is listed under Bio-Fiber or Space-age Mud and Wattle.

Walls designed to sit on a slab on the ground will be easiest to build with the following distances for the slab extension on the outside of the preliminary steel uprights (D1). A well defined seat for the exterior skin of cement and steel outside the insulation (D2) is also helpful. The horizontal bars were placed on the inside, thus, D1 is calculated as .357 cm, for welded wire, plus .6 cm for round bar which holds stiff foam insulation away from the welded wire, which ensures that the welded wire is inside the plaster, plus insulation thickness of 5 cm in this warm climate, for a total D1 = 6 centimeters (2 3/8"+). Two inches (5 cm) is sufficient for D2.

Walls lean inward slightly. Angle measurement is accomplished by making a right-angle out of wood which is tall enough to reach from the floor to the top horizontal bar. The inward lean is measured by how far the 90 degree angle point is in from where the vertical steel exits the slab. A free-standing, self-supporting jig is easy to nail together in a few minutes. The inward slope was started by adjusting the steel protruding from the floor and then lashing the tall verticals to them. Approximately vertical is far easier than an exact inward slope.

Frank designed the walls with an inward slope because he liked the added strength. He also did it for the pure fun of it. The angle is slight and some don’t notice it at all. Doors and windows, being perpendicular, provide some subtle finish details, mostly at the corners. Corners of flat rectangular planes either protrude or set into curved planes, depending upon point of view. Small, flat planes, like light switches and wall plugs, require an extension of flat finish surface beyond the utility itself. The box cover, or wall plate, needs a flat area to lay nicely against the wall. The flat finish area should be slightly larger than the wall plate. Be sure to locate electric boxes with this in mind.

The home of wood, stone and ferrocement, above, is a rectangular floor design with curves and straights in wall and roof. Visual contrast to the preceding drawing, with its curved floor plan, points to a design choice arena limited only by imagination.

Structures such as these are not all drawn on paper. A person with a pioneering spirit may sketch the structure using steel and four dimensional time-space from the start. In the next photo; an old pipeline yielded the raw materials for the home of Robin Gauss, great grandson many generations into the present from the famous scientist.

The motto striving forward to salvage pipe on this muddy mountain was given to us by Mahatma Gandhi, “Far better to be stricken with bitter pain and frustration from failure than to be a poor soul without imagination and afraid to explore.”

Curves in the top wall line are scaled from a drawing with a ruler. The simple idea is to make a drawing of a particular wall and then measure the height on the drawing where one needs to know the height while building. For example: If one-fourth meter equals one centimeter on the drawing, then one meter equals four centimeters, etc. A length of reinforcing steel tied to the vertical re-bars, at the height scaled from the drawing, transfers the curve from plan to reality.

The grout lines between stones can be cleaned with soil, fingers and whatever else works. Plastic sheeting protects the stone walls and keeps them clean while the roof plaster is being placed. Cut a sheet of plastic and clip the upper edge so a piece of #3 re-bar (.95 cm) and attach the re-bar with plastic sheeting to the underside of the roof steel on both side of the stonework.

These structures were built at an interesting historical moment; a couple hundred thousand years after the Human and Chimpanzee families went their separate ways. Humans colonized this area from two separate directions; across the Pacific land bridge from Asia to Alaska, and across the early Atlantic sea routes from Ireland to Nova Scotia. A second Human migration from the Alaskan north made it as far south as the Russian River where it meets the sea near Sebastepol, California. Atlantic sea routes expanded around the horns of Africa and South America during this later period.

The photos capture the exciting moment of people meeting from the South and the North. We did not yet know the complexity of our roots. A huge migration from the south was just beginning, most everyone was too busy raising families and avoiding or healing from the hell of war to clearly see the enormity of surrounding events.

Inocente, a southerner wielded a shovel with his new northern friends. “NorteĖos,” in his language, espaĖol. Mateo, spanish for Mathew, is pictured donning his uniform of the day; he plans to create structural art and leave a message in the far distant future. The net behind Mathew is a camouflage net.

This small earth covered home is the second built behind camouflage netting, which was provided by a war veteran who said he fought for freedom. People in all living generations joined together to build this home and communicate to the future that there are always some humans living beyond war and the bizarre desire for dominion over Mother Earth.

The government, as always, sought to squash. Inocente’s country massacred college students in the streets. Ours still sends the young to an unending stream of war and continues to help pillage the planet for profit. Mathew knew that free artistic expression and a life committed to great fun are the only voices that will ever be heard over the twin dins of war and greed, which convert a beautiful planet to equations defining short term profits. Good friend Mathew has passed away yet his statement will endure for many centuries. Contrast Mathew's work to General Motors bankrupt condition in the first decade of the 21st century, and remember the State of California's unsuccessful mid 20th century attempt to sue General Motors for altering the California culture by buying up all the small rail transportation and shipping it to Brazil. Why did General Motors buy up all the small local rail lines? A freeway culture buys more automobiles and uses more oil, rubber, steel glass, etc.

There are two subjects behind Mathew I still find more interesting than the camouflage. A group of friends across the canyon singing and laughing, “We see the camouflage! Where’d you find camouflage? We see you.” Examination of the hill behind Mathew reveals it is a plane tilted upward. A sedimentary sandstone and clay ridge thrown back by the grinding interface of continental plates and then exposed by weather. It has been made clearly visible by a recent fire. Fire and earthquake are among several colossal natural forces compelling choice of ferrocement.

The old WWII veterans in the local building department were fascinated to see safe, timeless, low-cost housing; they were friends who actually helped. The government studies graduates who replaced retiring vets had marching orders to crush anything that didn’t conform. We knew the camouflage didn’t really work and we laughed, too, led by the melody of Mathew’s musical laughter.

Government studies grads? Yikes! They are as serious as robots. Anything out of the box is to be put back in and/or punished; apparent motive is some sort of perverse punisher’s pleasure, plus regular pay and resumé enhancement from increasing the tax base. The Santa Barbara city and county government employees quashed a home-grown group of small businesses that specialized in fire resistant and earthquake safe homes and water tanks, these small businesses were chased out of a region that needs quality hillside water reservoirs and is prone to both fire and earthquake.

While all this may appear on the surface to be somewhat irrelevant to ferrocement construction, it does illustrate what attempts to build with ferrocement experienced during the latter half of twentieth century California. Perhaps additional details of those actual events will fit somewhere further along in this construction manual. At this point there are construction details in the photos that should be examined before focus slips too far into ecological economics and discussion of a sustainable culture.

A stranger came by the job one day, introduced himself, and asked if he could look around. I agreed without hesitation and continued with whatever the job was that day. I couldn’t help but notice that he kept looking at the tops of the windows and doors. After a long and thoughtful pause he turned to me and asked how it was done.

“How what was done?” I asked.

He informed me that he had spent his entire adult life repairing stone churches which had been damaged in the second world-wide war. He pointed to the top of a window and said that he had never seen stone work extend across an opening as if the opening were not there. He wanted to know what held the wall up when only air was below.

“Windows and doors in stone walls are usually capped with one long stone or built with an arch at the top, similar to an arched brick window or door opening,” he said.

When I explained how it was done he became quite excited and, on the moment, proclaimed me to be a genius.

Well, everyone likes to be considered a genius, including me. The truth is, however, I am a ferrocement tradesman. In my quiver of ideas and techniques is knowledge about the strength of double planes, separated so that they oppose each other in tension and thus are very strong. It is the exact same idea as a hollow sailboat mast except the opposing planes are flat, as illustrated in the following graphic explanation.

Number four reinforcing bar (1.2+ cm), welded in a pattern as illustrated, is very strong. Although welding is not necessary structurally, it does create a stable unit to work with. Notice that the weld is shown on one side only. When the entire grid has been welded one can then go back and do the other side.

Why weld one side only? The weld shrinks as it cools and this force is very large. A window reinforcing unit which had warped from the shrinkage could not be straightened by the weight of a heavy-duty delivery truck. Spacing between the longer bars is 5 - 10 centimeters (2 - 4").

Door or window opening top steel viewed from the end reveals the mortar form boards which hold fresh mortar and stone in place. The anchor bolt holding the form board up is for the finish window or door frame, when the wall is complete. The temporary form wood is about 2 centimeters thick. Be sure the anchor bolt threads and length are correct for the actual frame. Vertical frame wood is placed after top and bottom. Extend reinforcing steel into wall as far as practical on both sides.

It is of utmost importance to stress that welding is in no way related to structural strength required by the material or the design. Welding is strictly for convenience. It helps keep the steel exactly where it is placed. Welded steel cannot slip as wire ties occasionally do. If the local government thinks the welds are a structural necessity then you will be forced to have a full-time inspector on the job being paid two or even three times the wage of the highest skilled person on the job. This inspector in many jurisdictions will be a relative of somebody “important.” Perhaps there will be room further on for a story about the new fire chief from New York, who sent his brother-in-law to clean my fire-break, at three times my wages. The Chief's bright idea to clean up my near-by flower farm occurred during this construction project, his plan didn't happen.

Bars welded in this manner to straight steel stock, such as angle iron, to fashion a girder, can never be welded on both sides of the round bar. Never! Shrinkage of the weld will pull the straight line around the bar slightly; though the bend at each weld is slight, the straight steel stock is no longer straight and never will be again.

“Never say never,” is a familiar admonition which actually holds true here, too. The shrinkage force described can be tamed to use by highly skilled people. Heavy iron can be bent or straightened using the shrinkage force of welding by first cutting away steel with torch, saw or grinder and then replacing the removed material by welding. The steel member is pulled toward straight when the weld that fills in for the removed material cools and shrinks. Cuts are made perpendicular to the bend direction. I once helped a well driller named Doug Enloe straighten some equipment which had been bent when I rolled with his rig over a cliff; this happened when the road I myself made collapsed. His patient eye and mechanical skills are equal to any artist.

Continue to chapter 3